Transmission, Manual

Clutch Master Cylinder Replacement

I was able to remove/replace clutch master cylinder without disturbing the brake booster or brake master cylinder using the following procedure:

- Pinch clutch fluid hose from brake master cyl, remove hose at top connection, quickly put an old piece of hose (with end previously plugged shut) on brake master cyl. to minimize fluid loss. Remove clutch pedal actuator rod & rubber cover.

- Disconnect hydraulic metal line at clutch slave cyl., disconnect line holding clip, remove the two bolts holding clutch master cyl. to firewall, using the metal hydraulic line as a handle, gently fish out old clutch master cyl. via underside of car.

- Replace the old rubber hose (928 International has the blue frabic covered ones), attach and tighten the metal hydraulic line (be sure to orient as per old one), put a 6' length of 3/16" nylon rope through one of the two cyl. mounting ears, form a knot on the engine side so rope will not pull through. Repeat for the other mounting ear hole.

- Fish the two rope ends up from the underside of car and put ropes through the two mounting ear holes in the firewall. Start new master cyl. up to final location from underside of car using the metal hydraulic line as a (gentle) handle.

- Pull ropes to get cyl. to final location. Use vise grip pliers (bit of cloth will prevent marring cyl. end) and clamp clutch pedal end of cyl., remove one rope start to engage 1 mounting bolt, repeat for other side. Tighten bolts. Replace clutch pedal rod, rubber cover & adjust. Replace the clutch slave cyl. line and the clutch master cyl. fill hose.

- Suggest pressure bleeding of system, but manual method will eventually work.


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Just replaced my clutch master cyl. Yesterday, using the above method. It sounds easier than it actually is. I finally managed to get the cyl. in place after loosing the booster and having a second pair of hands to hold the cyl. in just the right place to bolt it in. Also replaced the clutch hose. Next time (more than 9 years from now, I hope) I will use the cheater method and just replace the guts and leave the cyl. bolted in place.

John Veninger
1990 928 GT

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If you are going to go to the trouble of having to fix a clutch master cylinder, it is crazy not to put a NEW one in. Rebuilds will not last as long and the new part is not very expensive.

Been there, done that.

Remember, soiled underwear is not a design problem. It clearly owes to insufficient owner maintenance.

Phk